9 Secret Levels You Missed In This Decade's Biggest Video Games

4. Niflheim & Muspelheim - God Of War

Though God of War has a defined progression if you just stick to the story quests, there are two additional realms to unlock if you want the best gear in the game.

Named Muspelheim and Niflheim, both require a number of Cypher pieces scattered across the world (all located on the main mission path), and in Muspelheim's case, you'll need the water in the main area to have dropped twice (done after visiting Freya the second time).

Both places house some of the best combat and content in the game.

Muspelheim is a six stage combat tower, getting progressively harder until you face a Valkyrie at the top. Conquering all these challenges unlocks variations on the stages themselves, rewarding you with specific materials to craft better gear if you're once again successful.

Niflheim is Sony Santa Monica's take on Dark Souls. A self-contained realm with its own set of rules, you'll need to navigate a poisonous mist, gather equipment to increase the time you can spend exploring, and bank as many Mist Echoes as possible back at home base before you perish mid-fight.

It's very grind-heavy once you unlock the three main sub-quests within the mist itself, but the result is the best armour in the entire game.